Gear mechanism units for a motor vehicle actuating drive are already known. They have a gear mechanism housing, an axle that is fixedly connected to said gear mechanism housing and a worm gear that is mounted on said axle in such a way that it can be rotated. The worm gear is provided at its outer periphery with toothing that meshes with a worm shaft, the latter being driven by a motor shaft or forming a unit with the motor shaft.
Gear mechanism units of this type are used in conjunction with window lift drives for example. The gear mechanism housing of known gear mechanism units often consists of PBT, i.e. a plastic with a 30% proportion of short glass fibers. The axle that is connected to the gear mechanism housing consists in many cases of steel in order to prevent the axle from deforming during operation due to toothing forces.
A window lift drive unit that is intended particularly for a cable window lift is known from DE 35 19 056 C2. This known drive unit has a housing in which are provided a worm gear that is driven by a drive motor and an output member that is displaced by the worm gear. Furthermore, a bearing pin that is mounted on one of the wall parts of the housing is provided for the worm gear. The bearing pin is positioned in a bearing bush that is riveted to the wall part. The output member or the worm gear is mounted on the outer peripheral surface of the bearing bush. Furthermore, the known drive unit is provided with a securing device which prevents the output member or worm gear from being pulled away from the bearing bushing.
Furthermore, a window lift drive is known from DE 88 12 399 U1. This has a gear mechanism housing in which a worm gear is mounted in such a way that it can be rotated on an axle that is fixedly connected to the gear mechanism housing, said worm gear being driven by an electric drive motor. Furthermore, the worm gear is arranged such that it is rotationally engaged with an output member by means of protruding driving cams in order to bring about the up-and-down movement of a window by means of a driving plate that is coaxially and also rotatably mounted on the axle. Furthermore, a driving plate is provided that has on its front face which faces away from the worm gear an axially protruding shaft collar that encircles the axle concentrically. Said shaft collar has an external lattice structure for positive rotational engagement both with a pulley of a cable window lift and with drive pinion of an arm-type or scissor-type window lift. The pulley or the drive pinion is provided with an internal lattice structure that corresponds to the external lattice structure of the shaft collar. These measures are intended to reduce component costs for cable window lifts and arm-type or scissor-type window lifts with a simple design that is suitable for automated production.
Furthermore, a motor gear mechanism drive unit that can be used in particular as a motor vehicle window lift drive is known from DE 295 13 701 U1. This known unit has a gear mechanism housing which has a support for a worm gear axle, on which a worm gear can be mounted.